1. Field of the Invention and Related Art Statement
The present invention relates to an apparatus for igniting a detonating primer with the aid of an electromagnetic wave comprising an oscillator for generating an electric oscillation signal, a transmitting antenna which is excited by said electric oscillation signal supplied from said oscillator to radiate an electromagnetic wave toward a receiving antenna provided on said detonating primer.
The igniting apparatus of the kind mentioned above has been described in Japanese Patent Application Laid-open Publication Kokai Sho 61-57,558. FIG. 1 is a schematic view showing this known igniting apparatus. The apparatus comprises a microwave oscillator 1 and a transmitting antenna 2 for radiating a microwave toward a plurality of igniting devices 3. Each of the igniting devices 3 includes a receiving antenna 4, a detonating primer 5, a signal cable 6 connected between the receiving antenna and the detonating primer, and explosives 7. The microwave radiated by the transmitting antenna 2 is received by the receiving antennas 4 of the igniting devices 3 and the received electric power is supplied via the signal cables 6 to igniting fuses of the detonating primers 5. When the igniting fuses of the detonating primers 5 are ignited, the main explosives 7 are exploded. It should be noted that the igniting devices 3 and explosives 7 are inserted into holes 8 formed in a surface 9 of the exploding site in such a manner that the receiving antennas 4 are exposed out of the holes 8.
In the known detonating apparatus explained above, the space in which the microwave propagates does not have a constant environment condition, so that the intensity of the electromagnetic field of the microwave radiated by the transmitting antenna 2 and received by the receiving antennas 4 fluctuates due to the complicated reflection and absorption of the microwave. Therefore, there is a problem that a sufficient amount of the electric power is not supplied to the receiving antenna 4 and the detonating primers 5 might not be ignited. Further, if the receiving antennas 4 receive spurious microwaves radiated from other transmitting antennas than the antenna 2 of the relevant detonating apparatus, one or more detonating primers 5 might be ignited erroneously.
Moreover, the microwave radiated by the transmitting antenna 2 spreads over a rather wide angle, so that there might occur serious problems of interference upon human beings, animals, plants and electric equipment.